The present invention relates generally to the field of apparatus for fiber optic communication, and more particularly, to through-bore fiber optic slip ring to provide transmission of an optical signal through a mechanically rotational interface with a through-bore.
An optic device to transmit optic signal from a rotating member to a stationary member is called fiber optic rotary joint, or fiber optic slip ring. There are many different types of fiber optic rotary joint, or fiber optic slip ring. Fiber optic rotary joint, or fiber optic slip ring are generally categorized as either an on-axis or an off-axis. In an on-axis fiber optic rotary joint the optic signal occupies the central space along the axis of rotation. In an off-axis type, the central space along the rotational axis is not accessible and the optic signal would not be allowed to path through this central space along the rotational axis. Usually there is a through bore along the rotational axis to provide routing space for hydraulics, pneumatics, RF, or other physical media. So the off-axis fiber optic sip ring is also called through-bore fiber optic slip ring. Application examples of through-bore fiber optic slip ring, include CT scan, MRI scan, tank turret, marine propulsion systems, helicopters, machine tools, and winches. While some of these applications require an infinite number of rotations in both directions others, such as a winch, only require a limited number of rotations in either direction.
Most of the single channel on-axis fiber optic rotary joint need two relatively rotatable members to hold two ends of optical fibers, one on each side of the rotating interface, that are opto-mechanically aligned along the common rotational axis. By employing the expanded beam technology, the light beam from the fiber is expanded when it is coupled through the rotational interface. The light beam is then refocused and aligned with the receiving fiber. The details are described in U.S. Pat. Nos. 5,039,193, 4,124,272, 5,633,963, and 5,949,929.
Most of multi channel on-axis fiber optic rotary joints also include two relatively rotatable members to hold two bundles of optic fibers, one on each side of the rotating interface, which are mechanically arranged around the common rotational axis. By using the expanded beam technology and de-rotating technology, like a Dove Prism, the light beams from fiber bundles can be transmitted through the rotational interface. The details are described in U.S. Pat. Nos. 6,301,405, 5,157,745 and 5,271,076.